Pistons for internal combustion engines



Feb. 4, 1969 T, ET AL PISTONS FOR INTERNAL COMBUSTION ENGINES SheetFiled July 1, 1966 Inventors 1). A. LAW LM Altorneys H. T. HILL ETALPISTONS FOR INTERNAL COMBUSTION ENGINES Feb. 4, 1969 Sheet Filed July 1,1966 A v N\ Feb. 4, 1969 T, HM ET A; 3,425,323

PISTONS FOR INTERNAL COMBUSTION ENGINES Filed July 1, 1966 Sheet 3 of 4Inventors H T. H \u.

I). A.LAw

a A tlorneys Ed). 4', 1969 1-, ETAL PISTONS. FOR INTERNAL COMBUSTIONENGINES Sheet Filed July 1, 1966 Fig.5

United States Patent 3,425,323 PISTONS FOR INTERNAL COMBUSTION ENGINESHarold Taylor Hill, Brockenhurst, and Douglas Alexander Law, Lymington,England, assignors to Wellworthy Limited, Lymington, England, a Britishcompany Filed July 1, 1966, Ser. No. 562,262 Claims priority,application Great Britain, July 9, 1965,

29,279/65- U.S. c1. 92-186 4'Cla1ms Int. Cl. F01b 31/08; F01p 1/04, 3/06ABSTRACT OF THE DISCLOSURE The present invention relates to pistons forinternal combustion engines, and in particular to oil cooled pistons inwhich oil is fed to the piston crown via the small end of the pistonconnecting rod.

According to the present invention there is provided an oil cooledpiston for an internal combustion engine wherein a separate transverseelongated bridging member spans the underside of the piston crown, andis secured at or adjacent its opposite ends to the piston ad acent theside wall thereof, the bridging member carrying a pick-up elementarranged to resiliently and slidingly engage the small end of aconnecting rod when assembled to the piston, and being provided thereinwith a transverse gallery communicating with the pick-up element andwith an oil gallery formed within the piston crown.

In order that the invention may be more readily understood, referencewill now be made to the accompanying drawings, in which:

FIGURE 1 is a vertical section through a piston according to oneembodiment of the invention, taken in the plane of the axis of thegudgeon pin bosses;

FIGURE 2 is a vertical section of the piston shown in FIGURE 1, taken ina plane normal to the axis of the gudgeon pin bosses;

FIGURE 3 is a transverse section on an enlarged scale of the bridgingmember taken on the line AA of FIG- URE 2;

FIGURE 4 is a fragmentary view on an enlarged scale of the bridgingmember taken in the direction of the arrow B in FIGURE 2; and

FIGURE 5 is a plan view of the crown of the piston shown in FIGURES 1and 2, with the spiral oil gallery indicated in phantom lines.

Referring to the drawings, the piston is made as a onepiece casting, forexample, from a non-ferrous metal such as an aluminium or magnesiumalloy, or from a ferrous metal such as a steel, a malleable or castiron, or spheroidal graphite iron. The piston comprises a crown 1, and aside wall including a ring carrier zone 2, a downwardly depending skirt3, and integral gudgeon pin bosses 4. A top piston ring groove carrierinsert may be cast into the zone 2 as shown, which, in the case of anon-ferrous piston casting, may be made of cast iron. Between the crown1 and side wall, are cast a pair of integral shoulders 5 disposed onopposite sides of the axis of the gudgeon pin bosses 4 as shown inFIGURE 2. A pair of blind tapped bores 6 are formed in each shoulder 5,and opening into the two shoulders between the pairs of bores 6 areports 7 and 8 formed by the opposite ends of an oil gallery 9 which iscast into the crown 1 in the form of a continuous spiral cavity (FIGURE5). For example, the radial inner end of this spiral gallery 9 may beconnected to the port 7, which comprises the oil inlet port, whilst theouter end of the gallery 9 may be connected to the port 8 whichcomprises the oil outlet port.

An elongated transverse bridging member 10, for example a cast alloybeam of U-shape as shown in FIG- URE 3, is secured across the shoulders5 by means of bolts 11 threaded into the bores 6. The bridging member10, at one end, is formed with a vertical passage 12 aligned andcommunicating with the port 7 and with an internal transverselyextending gallery 13, which, in turn, communicates at its inner end witha vertical cylindrical cavity 14 in the central region of the bridgingmember 10. Within this cavity 14 there is slidably located an oilpick-up element or slipper 15 formed, for example, from steel, bronze,or a light alloy, which is normally urged by means of a spring 16 intoengagement with bearing surface 17 formed on the upper surface of thesmall end of a piston connecting rod (not shown). The pick-up element 15is provided with a vertical gallery 18 which communicates with thetransverse gallery 13 via a cross bore 19.

The opposite end of the bridging member 10 is formed with an open endedpassage or vent 20 aligned with the outlet port 8.

When in operation in an internal combustion engine, engine oil underpressure is fed up through internal passages in the connecting rod tolubricate the small end thereof, and some of this oil passes up throughan opening in the bearing surface 17, through the pick-up element 15which makes a sliding seal with the bearing surface, transverselythrough the bridging member 10, through and around the spiral gallery 9,and then back into the engine through the vent 20. During the passage ofthe oil through the gallery 9, the oil acts as a coolant by absorbingheat from the piston crown and also from the back of the upper pistonring groove.

By mounting the pick-up element 15 in a bridging member 10 which issimply bolted into the piston and which incorporates some of the oilways of the cooling system, the manufacture of the oil-cooled piston,and also of the gudgeon pin used with the piston, is considerablysimplified. Moreover, the pick-up element 15 may be used to convey oildirectly into a cavity under the piston crown for cooling purposes,instead of, or in addition to, conveying oil through the transversegallery 13. In the former case, the transverse gallery 13 may be blankedoff or omitted, and the pick-up element 15 would have an axial openingin its upper end.

When providing this alternative or additional manner of cooling theunderside of the piston crown, the bridging member 10 may be widened soas to form a floor to the cavity under the piston crown. Cooling oil fedthrough the pick-up element 15 will then be able to splash or shake upand down between this floor and the underside of the crown, in the wellknown manner of a cocktail shaker, so providing the maximum coolingeffect before the oil escapes from the piston.

It will be understood that various modifications may be made withoutdeparting from the scope of the invention. For example, the bridgingmember may extend generally parallel to the axis of the gudgeon pinbosses instead of transverse thereto. Although a single spiral oilgallery has been shown which is cast into the piston crown, the gallerymay alternatively be circular or of any other desired configuration, andmore than one gallery may be provided. The or each gallery may be castinto the crown using a soluble core technique, may be produced bycasting a pipe or pipes into the crown, or may be produced in any othersuitable way.

The or each gallery may be disposed solely in the region of the pistonring groove carrier zone, or in the region of the crown, or both, or maybe omitted, the oil being fed into a cavity between the under surface ofthe crown and the bridging member.

We claim:

1. An oil cooled piston for an internal combustion engine, including apiston crown, a side wall depending from and integral with said pistoncrown, and gudgeon pin bosses integral with said side wall, an oilgallery comprising a continuous elongated tubular cavity within thecrown, said gallery having an inlet port and an outlet port, a unitarydetachable transverse elongated bridging member within the piston whichspans and is spaced from the underside of the piston crown, and issecured by its opposite ends to internal mounting faces on the pistonspaced apart on opposite sides of the piston axis and disposed adjacentthe side wall, said bridging member engaging the piston only at saidmounting faces, the bridging member carrying, intermediate its oppositeends, a depending pick-up element which is movable relative to thebridging member toward or away from the piston crown, means adaptednormally to resiliently bias the pick-up element in a downward directionaway from the piston crown, the pick-up element being provided thereinwith a downwardly opening oil gallery, communicating with an inlet endof a transverse oil gallery formed wholly within the bridging member andspaced from the underside of the piston crown, said transverse galleryhaving an outlet port at one of said opposite ends of the bridgingmember communicating with the inlet port of the oil gallery formedwithin the piston crown.

2. A piston according to claim 1, which comprises a light alloy casting,wherein said bridging member comprises an alloy casting in the form of agenerally U section beam, extending generally normally to the gndgeonpiston axis, having first and second upwardly directed faces disposedrespectively at opposite ends of said beam, the outlet port of thetransverse oil gallery within the beam Opening into said first face, andan inlet port, which terminates the upper end of a downwardly extendingopen-ended vent in the beam, opening into said second face, said firstand second upwardly directed faces mating respectively with first andsecond downwardly facing shoulders intergral with the side wall onopposite sides of the crown and constituting said mounting faces, thebeam being secured within the piston solely at the mating faces by boltslocated in the region of said mating faces, the oil gallery within thecrown comprising a continuous spiral oil gallery, the inlet port ofwhich opens into said first shoulder in alignment with the inlet port ofthe transverse gallery in the beam, and the outlet port of which opensinto said second shoulder in alignment with the inlet port of said vent.

3. A piston according to claim 2, wherein the beam is provided with avertical cylindrical cavity in its central region communicating with thetransverse gallery, within which cavity of the oil pick-up element istelescopically slidably mounted, and wherein said biasing meanscomprises a spring located within the cavity.

4. An oil cooled alloy piston for an internal combustion engine,including a piston crown, a continuous elongated tubular oil gallerycontained wholly within the crown, and having an inlet port at one endand an outlet port at its opposite end, a side wall depending from andintegral with said crown, a pair of transversely spaced gudgeon pinbosses integral with said side wall and aligned with respect to a commontransverse axis, first and second downwardly facing shoulders integralwith and adjacent the side walls, spaced apart on opposite sides of thetransverse axis of the gudgeon pin bosses, and disposed between theperiphery of the underside of the crown and the gudgeon pin bosses, saidinlet port opening into said first shoulder and said outlet port openinginto said second shoulder, a separate transverse elongated bridgingmember disposed within the piston, located wholly externally of saidcontinuous elongated tubular oil gallery, extending between saidshoulders, spanning and spaced from the underside of the crown, saidbridging member having, respectively, first and second upwardly directedfaces at opposite transverse ends thereof, mating respectively with saidfirst and second shoulders, said bridging member engaging the pistononly at said shoulders, and being secured to the piston only in theregion of said shoulders by bolts, said bridging member being providedwith a vertical cylindrical cavity in its central region within which adepending oil pick-up element is telescopically slidably mounted, acompression spring disposed around the pick-up element within the cavityadapted normally to resiliently urge the pick-up element downwardly awayfrom the crown, said element having a generally vertical downwardlyopening oil passage therein communicating at its upper end with saidcavity, a transverse oil gallery formed wholly within the bridgingmember communicating at one end with said cavity, extending from saidcavity within the bridging member to a position adjacent said firstupwardly directed face, and at its other end opening into said face inalignment with said inlet port in the first shoulder, a downwardlyopening vent in the opposite end of the bridging member, opening intosaid second upwardly directed face in alignment with the outlet port insaid second shoulder, whereby there is provided a flow path for coolingoil, said flow path comprising, in the direction of oil flow, thepassage in the pick-up element, the cavity in the pick-up element, thetransverse gallery in the bridging member, the inlet port, thecontinuous elongated tubular oil gallery in the crown, the outlet port,and the vent in the bridging member.

References Cited UNITED STATES PATENTS 1,547,687 7/1925 Rohwer 123-41351,669,290 5/1928 Czock 123-4138 2,442,438 6/ 1948 Robinson et a1.123-4138 2,815,011 12/1957 Holt 123-4138 FOREIGN PATENTS 202,289 2/ 1959Austria.

19,815 9/ 1915' Great Britain. 702,002 1/ 1954 Great Britain. 737,714 9/1955 Great Britain.

MARTIN P. SCHWADRON, Primary Examiner.

I. C. COHEN, Assistant Examiner.

US. Cl. X.R. 123-4135, 41.38

